Spatio-temporal variation of nitrate based on Landsat 8 in Playa Colorada bay, Sinaloa, Mexico.

Characterizing water quality in coastal waters through spatial observations is challenging, due to spatial and temporal variations in water composition. Nitrate, an important compound for water quality assessment, has received little attention in estimates made from satellite measurements, even though it can be estimated using models generated from multispectral images. Since nitrate is a non-optically active parameter that can be correlated with optically active parameters, it was related to bands of the visible and infrared spectrum, captured in Landsat-8 images, and used to generate empirical models to estimate the spatio-temporal variation of nitrate concentration in the Playa Colorada Bay, in the state of Sinaloa Northwest Mexico. Four sampling campaigns were performed, two in spring and two in fall. Nitrate nitrogen (NO3-N) concentration ranged between 0.69 and 1.80 mg/L, values higher than those recommended in the Mexican ecological criteria of water quality for the protection of marine aquatic life in coastal areas. Generated models showed a significant relationship (P < 0.05) between NO3-N and band reflectance in the infrared (band 5) and short-wave infrared (band 6 and band 7) spectra of Landsat-8 imagery. The B6 band appeared in all models selected to estimate NO3-N in the bay. These results evidence the potential of Landsat-8 images for the estimation of nitrate in the coastal waters of Sinaloa, México.

Applying EFDC Explorer model in the Gallinas River, Mexico to estimate its assimilation capacity for water quality protection.

Sanitary and industrial wastewater discharged into rivers, is a general problem that occurs in most of the world and Mexico is not the exception, the main goal of this research is to determine based on simulations of pollutants concentrations, the assimilation capacity of the Gallinas River against discharges of agricultural and industrial wastewater from the cultivation and processing of sugar cane under two different hypothetical simulation scenarios, based on reproducing two well know scenarios. In sugarcane cultivation, large quantities of fertilizers are used whose main active components are based on nitrogen or phosphorus compounds, therefore, the wastewater resulting from sugarcane processing contains a high organic content from 20 to 40% of inorganic compounds, such as nitrogenous substances, organic acids, and phosphorous sulfates. For this reason, the physical-chemical variables of interest analyzed in this work are the PO[Formula: see text] (phosphate), NO[Formula: see text] (nitrate), and DO (dissolved oxygen). With the simulation results according to each scenery, it can be determined, that despite the continuous discharge of polluting elements, the Gallinas River has a good assimilation capacity thanks to reaeration processes that permit efficient recovery of the dissolved oxygen in the water column. Gallinas River is located in the region known as the Huasteca Potosina, this investigation is relevant for the region due to the River is of vital importance being the main tributary that allows socioeconomic development activities in this zone. To carry out the simulations, was used the Explorer Modeling System 8.4 (EFCD) model and was performed two samplings campaign along 15 km in the water body to calibrate the numerical model to represent the dry and wet seasons during May and September respectively named as calibration scenarios.

Contamination Level and Spatial Distribution of Heavy Metals in Water and Sediments of El Guájaro Reservoir, Colombia.

Heavy metals have become a subject of special concern worldwide, mainly due to high persistence in the environment, toxicity, biogeochemical recycling and ecological risk. Therefore, the objective of this investigation was to analyze the spatial-temporal distribution of heavy metals in water and sediments to determine the environmental status of El Guájaro Reservoir, where such studies have not been developed. Two measurement campaigns (dry and wet period) were carried out and eight sampling stations were selected. A comparison of water and sediment quality parameters with existing national and international regulations was done. Also, heavy metal distribution maps were generated, and the geoaccumulation index was calculated to identify sources and sediments contamination level. Based on the obtained results, agriculture and mining activities are the main causes of the reservoir contamination. This metals levels could be a potential risk for the aquatic life and the populations that are supplied from this water body.